DIFFUSION OF IMPURITY EXCITATIONS IN SUPERFLUID AND SOLID H-3-HE-4 MIXTURES

Starting from the system of linearized kinetic equations, the exact ex pressions for the spin and mass diffusion coefficients and thermal dif fusion ratio in quantum mixtures of helium isotopes with any degree of degeneration is obtained From the general expression the various limi ting expressions have been obtained, which ape determined by various r elations between collision rates of quasiparticles. The results of the calculations are compared with available experimental data. It is sho wn that in the low-temperature region, where an impuriton gas is one-c omponent, the relaxation of concentration of He-3 in superfluid He-3-H e-4 mixtures is determined by the acoustic and dissipative collective modes with an effective diffusion coefficient. From the general relati on, the expression for a spin diffusion coefficient in solid He-3-He-4 quantum mixtures is derived The comparison of the results obtained wi th the experimental data makes it possible to find a numerical value f or the width of the impuriton energy zone.